Heretofore, a liquid-crystal display device has come into wide use as a thin type display device. In the liquid-crystal display device, however, a display is presented in such a way that light from backlight is controlled by a liquid crystal. It is therefore difficult to display a perfect black level, and to make contrast sufficiently high.
On the other hand, an organic EL display of self-emission type has emission and non-emission controlled for every pixel in accordance with the contents of a picture. Therefore, the black level emitting no light can be expressed, and the contrast can be heightened to realize a high image quality (see WO 2006/020511).
Here, in the organic EL display, a light emission intensity and a light emission frequency differ for every pixel, so that the difference of degradation occurs between a pixel which emits bright light frequently and a pixel which hardly emits light. In addition, burn-in has been liable to occur in the pixel which emits the bright light frequently.